by Michael Winter, USA TODAY

by Michael Winter, USA TODAY

For only the third time in space history, Earth has been photographed from the outer solar system, NASA said Tuesday.

The space agency released the image of Earth, the moon and part of Saturn taken Friday by the Cassini probe, which has been orbiting the giant planet for 15 years.

The image, shot beneath Saturn's rings, shows Earth as a blue dot, 898 million miles away. A magnified version shows Earth and the moon more clearly.

NASA explains what you see and what was done technically:

The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are clearly seen; the limb of Saturn and the F ring are overexposed. The "breaks" in the brightness of Saturn's limb are due to the shadows of the rings on the globe of Saturn, preventing sunlight from shining through the atmosphere in those regions. The E and G rings have been brightened for better visibility.

Preparing for what was undoubtedly the ultimate, most far-out selfie ever snapped, scientists and engineers at the Jet Propulsion Lab in Pasadena, Calif., gathered at the appointed moment and waved for Cassini. That explains NASA's title for the photo: "The Day the Earth Smiled."

NPR's Joe Palca described the image as "not that scientifically interesting, but it's so cool."